This invention relates generally to x-ray sources, and more particularly to an x-ray source bearing assembly for facilitating heat dissipation.
In medical x-ray imaging, an x-ray source is utilized for generating x-ray beams that pass through an object being imaged. More specifically, an x-ray source projects a fan-shaped beam which is collimated to lie within an X-Y plane of a Cartesian coordinate system and generally referred to as an xe2x80x9cimaging planexe2x80x9d. The x-ray beam passes through an object being imaged, such as a patient. The beam, after being attenuated by the object, impinges upon an array of radiation detectors. The intensity of the attenuated beam radiation received at a detector array is dependent upon the attenuation of the x-ray beam by the object. Each detector element of the array produces a separate electrical signal that is a measurement of the beam attenuation at the detector location. The attenuation measurements from all the detectors are acquired separately to produce a transmission profile.
A typical x-ray source includes an x-ray tube which emits an x-ray beam at a focal spot. Known x-ray tubes include a cathode aligned with a rotating target anode. An electron beam generated at a cathode emitter is directed towards the anode and forms a focal spot on an anode surface. As a result, x-ray beams are emitted from the anode.
The target anode is rotated by a rotor shaft coupled to a motor. Specifically, the rotor shaft extends from the motor, through a bearing housing, to the anode. The shaft is supported by bearings contained in the bearing housing, and rotates relative to the bearing housing.
During operation, the motor rotates, or drives, the rotor shaft to rotate, and the target anode rotates with the shaft. Rotation of the shaft on the bearings results in heat being generated in the bearing housing. The heat generated by the rotating shaft should be dissipated in order to avoid failure of the x-ray tube bearings.
In one aspect, an x-ray source including a cooling medium pool for cooling rotor shaft bearings is provided. In an exemplary embodiment, the x-ray source includes a target anode, a rotor shaft coupled to the target anode, and a motor coupled to the rotor shaft at an end of the shaft opposite the target anode. The source further includes a bearing housing including a rotor bore. The rotor shaft extends through the rotor bore and is supported therein by a plurality of bearings. The bearing housing and the rotor shaft form a cooling medium pool so that as the rotor shaft rotates, a cooling medium in the cooling medium pool is radially displaced.
In another aspect, a method for assembling a rotor shaft and a bearing housing is provided. The bearing housing has a rotor bore therethough and includes a first bearing containment section and a second bearing containment section. The method includes the steps of locating the first bearing containment section so that the rotor shaft extends therethrough and so that an outer race of the first bearing containment section aligns with an inner race of the rotor shaft, and locating the second bearing containment section so that the rotor shaft extends therethrough and so that an end section of the second bearing containment section mates with the first section, and welding the first bearing containment section to the second bearing containment section.
In yet another aspect, a bearing housing and rotor shaft is provided The bearing housing includes a rotor bore, and the rotor shaft extends through the rotor bore and is supported therein by a plurality bearings. The bearing housing and the rotor shaft form a cooling medium pool so that as the shaft rotates, a cooling medium in the pool is radially displaced.